1. Field of the Invention
The present invention relates to a manufacturing method for exposure mask in semiconductor field, a generating method for mask substrate information, a mask substrate, an exposure mask, a manufacturing method for a semiconductor device and server.
2. Description of Related Art
As the semiconductor devices are miniaturized, there is a demand for micronization in the photolithographic process. Already, the device design rule is as small as 0.13 μm, and the pattern dimension is about 10 nm and a very severe precision is requested. As a result, recently, problems are arising in photolithography in the semiconductor manufacturing process.
The problems are about flatness of mask substrate used in the photolithographic process as one of the factors relating to enhancement of precision in pattern forming process. That is, as the micronization is advanced, the margin for the focus in photolithography becomes smaller, and therefore the flatness of the mask substrate can be no longer ignored.
Accordingly, the present inventor accumulated studies about flatness of the mask substrate, disclosed the following.
Surface shapes of mask substrate are various, including, even in the same flatness, convex type, concave type, saddle type and mixed type. Therefore, even if the flatness is the same, when the mask substrate is fixed on the mask stage of a wafer exposure apparatus by vacuum chuck, the mask substrate may be largely deformed, or little deformed, or inversely the flatness of the mask substrate may be improved, depending on the conformity with the mask stage or vacuum chuck.
This is because the flatness of the mask substrate after chucked depends on the surface shape of the mask substrate before fixed, and also varies with the part of the mask substrate where the mask substrate is chucked by the vacuum chuck even in the same mask substrate. Depending on the surface shape of the mask substrate, the flatness of the mask substrate may be largely degraded by chucking the mask substrate on the mask stage of the wafer exposure apparatus.
It has become found that the product yield was lowered when semiconductor devices were manufactured by using an exposure mask obtained by forming a pattern on such mask substrate with low flatness.
The inventor compared the flatness of mask substrate before and after chucking the mask substrate on the mask stage of the wafer exposure apparatus, and confirmed that the flatness of the mask substrate was degraded after chucked depending on the surface shape of the mask substrate, and found that such degraded flatness was a major cause to lower the product yield.